1. Preheat oven to 350 degrees. Toast almonds on a rimmed baking sheet 8 to 10 minutes; when cool enough to handle, chop and set aside. Bring a large pot of salted water to a boil; add pasta and cook according to package directions until al dente. Reserve 1 1/4 cups pasta water; drain.

2. Meanwhile, in a large straight-sided skillet, heat 1/4 cup oil, garlic, and red-pepper flakes over medium until garlic is just fragrant, about 1 minute. Add chard leaves and stems in a few batches and cook, covered, stirring occasionally, until just wilted, 4 to 6 minutes. Add almonds, lemon zest and juice, and reserved pasta water. Add cooked pasta and remaining 2 tablespoons oil; toss to coat. Stir in pecorino; season with salt and black pepper. Serve with more cheese.